Jim Cronin, campaigner against the illegal trade in primates and founder of the animal sanctuary Monkey World, in Dorset, has died aged 55 of liver cancer. Working with primates has a long history of producing strong, even iconoclastic, personalities - from Jane Goodall to Diane Fosse and Karl Amman - and Cronin, an irascible, headstrong and passionate man, was no exception.

Born of Irish-Italian parents, he was brought up on the banks of the Hudson river in Yonkers, near New York. After graduating from St Denis school and Lincoln high school, he took odd jobs as a lift constructor and a removals man before, quite literally, falling into primatology. An accident while moving a grand piano left him with his leg in traction, and when he recovered he took a job looking after the primates at the Bronx zoo.

In 1980, he moved to Britain to take up a job at Howletts Wild Animal Park, near Canterbury, Kent, where the owner, John Aspinall (obituary, June 30 2000), was busy rewriting the rules on keeping gorillas in captivity. Instead of washing down concrete floors with disinfectant and segregating animals, Aspinall kept them on thick beds of hay in large family groups. The result was spectacular breeding success. Cronin thrived in this unconventional environment and set up a primate breeding programme under Aspinall's auspices despite his lack of academic qualifications.

After seven years at Howletts, Cronin's streak of zealous anger about the fate of captive chimps - combined with a natural showmanship - led him to start rescuing orphan chimpanzees being used by Spanish beach photographers. Early undercover television footage reveals his refusal to back down in the face of physical and verbal assaults and, all too often, official indifference.

At the beginning of this crusade, Cronin bought a plot of gravelly heathland, a former pig farm, at Wareham, Dorset. He got planning permission to build his first enclosures, and in 1987 opened Monkey World. Initially, it became home to nine rescued chimps. At the last count, it was home to 160 primates from 13 countries, including the largest group of chimpanzees outside Africa and the most important breeding group of Borneo Orangs outside Borneo.

Learning from his experience at Howletts, Cronin wrote his own rules on what Monkey World was to be. Enclosures at the 65-acre sanctuary were spacious and designed using wood, mats and rope. He described the physically and emotionally scarred chimps - some tortured with cigarette butts, force-fed tranquilisers, isolated and beaten - as having the same psychological problems as abused humans. They needed to learn to trust again, and required careful rehabilitation before integration into family groups. An initial decision was taken not to breed - the abused chimps would have been poor mothers - and Monkey World was one of the pioneers in primate birth control, including slow-release implants.

The growing success of Monkey World, which now attracts half a million visitors a year, acted as a springboard for Cronin's rescue and recovery campaigns around the world, from Turkey to Taiwan. High-profile schemes such as Adopt a Chimp and Cronin's typically up-front and forceful lobbying of people like prime minister Margaret Thatcher about the illegal trade in chimpanzees soon brought him to the attention of television programme-makers. This interest culminated in the long-running Animal Planet series, Monkey Business, first transmitted in 1997, a popular animal docu-soap about day-to-day life at Monkey World, which has been shown all round the world.

Cronin's larger-than-life approach, his endless campaigning and bolshiness inevitably led to comparisons with other TV wildlife personalities, such as Australian Steve Irwin (obituary, September 5 2006), although he never quite achieved the same celebrity status or notoriety. His forthrightness also earned him some enemies in the primatology world, although few doubted his passion and conviction.

In 1993 Cronin met Alison Ames, a fellow American and a behavioural expert who had studied biological anthropology at Cambridge University. She arrived at Monkey World to discuss fencing techniques and the couple married in 1996. They ran Monkey World as a joint operation, coordinating rescue missions around the world, running campaigns against the animal smuggling trade and co-starring in television series. In 2006 Cronin was awarded an MBE for services to animal welfare.

He is survived by Alison, his daughter Eleanor from his first marriage, mother Margaret, brother John and sister Deborah. It is understood his ashes will be returned for burial to the sanctuary he founded.

· James Michael Cronin, conservationist and campaigner, born November 15 1951; died March 17 2007